Project Summary/Abstract Adolescent idiopathic scoliosis (AIS) or late-onset scoliosis affects ~3% of the pediatric population, presenting with body curvature without overt structural defects of vertebral units. More severe AIS cases require surgery to correct the deformity and prevent co-morbidities including compromised pulmonary function. Despite this significant burden to the society, there is limited understanding of the genetic basis of AIS. We propose to delineate the molecular genetics and generate animal models of AIS in zebrafish (Project 2) by synergistic interactions with human genetic (Project 1) and genomic (Project 3) studies. Having a well- annotated genome and plentiful, transparent progeny, zebrafish afford a powerful vertebrate model to study AIS by employing forward and reverse genetic approaches. Our preliminary genetic screen for chemically induced mutations has uncovered 31 recessive adult mutants with scoliotic features that define 25 complementation groups. Using massively parallel sequencing to analyze the genome of one scoliotic mutant, we identified a non-synonymous mutation in the kinesin family member 6 (kif6) gene. We propose to continue this productive screen to define genes required for normal spine development in zebrafish. We will identify the molecular nature of isolated mutants and characterize the defects at embryonic and tissue levels. The scoliotic zebrafish mutant loci will become candidates in human genetic (Project 1) and genomic analyses (Project 2). Towards validating candidate loci identified in human AIS patients and genomic studies, we will leverage the gene targeting and editing methods we recently helped to improve, to engineer null mutations and/or humanized non-synonymous mutations in zebrafish. By combining the complementary expertise of the participating research groups, advances in human genetics and genomics with the strengths and methodological innovations in the zebrafish model, this program will provide the first atlas of genes critical to proper spine development in general and to AIS specifically. We will also create tissue bank, genomic databases and generate animal models that will altogether open new avenues to understand, diagnose and eventually prevent or treat AIS.